In the manufacture of semiconductor optoelectronic devices it is well known to mount a light emitting diode onto a copper heatsink. The excellent thermal conductivity of the copper enables it to dissipate much of the heat generated during the operation of the device. In order for the diode to benefit from the heatsinking capabilities of the copper, a good bond must be formed between the diode and the heatsink. Therefore, the mounting surface of the heatsink should be flat, smooth and defect-free.
Also, many such devices are coupled with an optical fiber. One such coupling comprises mounting the diode on the top surface of the heatsink and butting the fiber against the front surface of the heatsink, which surface should be at a 90.degree. angle from the top surface. This requires that the top surface and front surface of the heatsink must be smooth and flat and also that these surfaces form a 90.degree. corner.
A problem with copper is that it is known to produce burrs when cut or machined. When the top surface of a copper block is machined, a burr is formed in the direction of the machining. Upon machining the front surface of the copper block, the first burr is removed but a second burr is formed in the direction of the secondary machining. It is virtually impossible, in such a method, to end up without a burr on the corner of the copper block. Also, typical machining methods, such as milling, leave the copper surfaces flat, but not smooth enough for semiconductor device mounting.
Precision grinding and lapping of the surfaces can product flat smooth surfaces, but the abrasive medium used typically becomes impregnated in the copper surface. This type of contamination can adversely affect the thermal conductivity of the copper. Also since the copper is typically metallized before bonding, this contamination has been found to cause problems with the subsequent metallization.
It would be desirable therefore to have an apparatus and/or method for imparting flat, smooth surfaces which form a sharp 90.degree. corner onto copper blocks to be used as heatsinks in the manufacture of semiconductor optoelectronic devices.